1. Field
Embodiments relate to cache management based on types of input/output (I/O) operations.
2. Background
In certain storage system environments, a storage controller (or a storage controller complex) may comprise a plurality of storage servers that are coupled to each other. The storage controller allows host computing systems to perform input/output (I/O) operations with storage devices controlled by the storage controller, where the host computing systems may be referred to as hosts.
The storage controller includes a cache that stores data so that future requests for that data from the host may be served faster. Data may be written to or read from the cache much faster in comparison to writing to or reading from the storage device. A cache hit occurs when requested data from the host can be found in the cache, while a cache miss occurs when the requested data cannot be found in the cache. Cache hits are served by reading data from the cache, which is faster than reading from a storage device coupled to the storage controller.
When a cache is low on space or segments, then the cache needs to evict data items from the cache and this eviction of data items from the cache is referred to as demotion. A cache replacement policy may be used to determine which data items in the cache are to be demoted to make room for new data items. A least recently used (LRU) policy demotes the least recently used data items first.